Someone showing you a folder of photographs of a paticular event, and you spotting a bunch of ones they've taken of themselves scantily clad / looking 'seductive / topless; and them knowing you just saw it.

My housemate went to attach something innocuous to an email, it popped up with the last folder she'd attached something from. It was full of naked pictures of herself she'd been sending her boyfriend. Oh, how we laughed.